The long term objective of this proposal is to develop a product to provide a physician, who is prescribing nutritional support to critically ill patients, with a daily assessment of the metabolic response of patients to his prescriptions. In particular, the first aim of this project is to demonstrate that net protein catabolism (PCR) can be calculated from BUN and serum creatinine, thereby avoiding technical problems associated with daily urine collections. The second aim is to develop computer software that will relate the measured clinical and metabolic responses observed in patients and visually display this information for the physician prescribing nutritional support. The third aim is to demonstrate that a daily review of the metabolic response of patients to nutritional support will optimize the consumption of pareneral solutions and improve the quality of patient care. These goals will be achieved by measuring protein balances (urine collections, intakes, losses, and change in body accumulation of urea) on nutritionally supported patients to validate protein balance estimates. These estimates use a single pool mathematical model of urea nitrogen and BUN and serum creatinine to calculate renal clearance, rates of urea production, and PCR. This model has been validated in renal patients. Also proposed is a usage analysis of parenteral solutions and prescription of nutritional assessment by determination of pharmacy disbursments and review of patient charts. It is anticipated that good correlation between estimated and measured protein balances will result and that these data when available to the physician will improve his nutritional prescription with respect to the patient's response to it. The results of Phase I will provide the criteria for designing commercial software during Phase II. This software will calculate the daily assessment of metabolic response and will be designed for use on the micro computers currently found in hospital intensive care wards.